If you're looking for more physiology stuff, the protein book and the keto book are must reads. The bromo booklet also covers a lot about bodyweight regulation (leptin) too. They're quite technical, but cover literally everything there is to know on the topics of protein and low carb diets. If you don't want to jump into the deep end, flex dieting is a good start, but if you've read RFL, listened to lyle's interviews and read most of the main site articles, there's not much more to it than that, but for a beginner it's a must-read. From Alan Aragon, I really liked his Girth Control book. Again, not for the rank novice who's looking for some really basic dieting strategies, but for someone who knows the basics and wants some more advanced stuff it's great.